A numerical taxonomic study of Armeria maritima (Plumbaginaceae) in North America and Greenland

Abstract

Principal components analysis, discriminant analysis, cluster analysis and two level nested analysis of variance were performed on 961 herbarium specimens of Armeria maritima covering the complete geographic range of the species in North America and Greenland. Among the monomorphic, self-compatible specimens combining coarsely reticulate pollen and papillous stigma, we recognized three subspecies. Along the Pacific coast from California to Vancouver Island, the single taxon ssp. californica is proposed, which includes the formerly described var. purpurea. In arctic and subarctic regions, ssp. sibirica, which includes var. labradorica, and ssp. interior are recognized as distinct entities. The latter has a restricted distribution and can be easily distinguished morphologically owing to its glabrous calyces. The morphological variation between ssp. californica and ssp. sibirica is continuous and some overlap occurs. The best diagnostic characters are two ratios: sheath length to flower head width and outer involucral bract length to flower head width. Geographic trends are obvious: a reduction in plant size with increasing latitude and an increase in frequency from west to east of hairy scapes and holotrichous calyces. The dimorphic and self-incompatible ssp. maritima is maintained because of its distinct breeding system (papillate stigma associated with finely reticulate pollen and smooth stigma associated with coarsely reticulate pollen). Subspecies maritima is only found in south Greenland and some specimens are morphologically similar to eastern monomorphic plants. Key words: Armeria maritima, North America, numerical taxonomy.